1. Field of the Invention
This invention relates to the field of reciprocating, multicylinder internal combustion engines having rotating power output crankshafts such as are used in powering automobiles, trucks, boats, airplanes and the like. More particularly, this invention relates to 4-cycle internal combustion engines of the in-line variety.
2. Description of the Prior Art
The operation of an internal combustion engine is fairly well known. Power is obtained from heat produced by the explosion of a fuel/air mixture within a cylinder through the driving of a piston therein whose reciprocating motion is translated into the rotary motion of the output crankshaft through connecting rods. In gasoline-powered internal combustion engines, the explosion is produced by a spark whereas in a diesel internal combustion engine the explosion is produced by the heat generated in the on cycle. In 2-cycle engines the cylinder is fed with a combustible fuel/air mixture for each upward stroke of the piston so that each downward stroke is a power stroke whereas in the 4-cycle internal combustion engine the power strokes are separated by downward strokes where the cylinder is charged with a fresh fuel/air mixture. In addition to the cylinder and the piston that reciprocates therein, the combustion chamber is generally considered to have associated therewith valves for passing the fuel/air mixture into the cylinder and exhausting the spent fumes therefrom as well as spark means for gasoline and other non-diesel fuel type applications as well as the various lines and wires normally associated with transferring fuel, air and electrical energy to an internal combustion engine
The connecting rod attaching the reciprocating piston, through the open end of the cylinder, to the rotating crankshaft is pivotally attached to the center of the piston by a wrist pin and is attached to the crankshaft at a displaced portion or offset thereof called a "crankshaft throw". This arrangement has always had problems associated therewith.
For instance, the angle of the connecting rod to the vertical at the middle of the piston travel causes a severe side thrust through the piston against the cylinder wall and causes substantial wear to the lower portion of the cylinder. Further, because of the long, narrow design of the connecting rod, a certain amount of flexing is developed when the engine is subject to high stress loads causing a weakening of the connecting rod and a loss of power in the engine output. Still further, the power impulse of the downwardly driven piston acts on a torque arm against the crankshaft which reaches a maximum approximately 75.degree. after top dead center (ATDC) and at an angle between the rod and the cylinder axis of approximately 15.degree. causing a loss of torque suffered as a result of the power being delivered through less than 90.degree. after top dead center (ATDC) of crank rotation and not in the same direction as the piston travel. Also, with only one piston and connecting rod per cylinder, in in-line internal combustion engines, a longer crankshaft is required for any number of cylinders. Finally, the length of the connecting rod needed to complete one revolution of the crankshaft throw and yet not strike the cylinder walls during reciprocation of the piston requires that the cylinders be spaced apart from the crankshaft thus requiring more metal and more weight in the overall engine construction.
The prior art has dealt with these problems only sporadically, see U.S. Pat. Nos. 1,372,955; 1,528,002; 1,905,754; 1,946,718; 3,200,800; 3,403,508, and 3,828,741. In some inventions, more than one connecting rod is tied together for a particular crankshaft throw, such as in U.S. Pat. Nos. 1,528,002; 1,905,754 and 1,946,718. However, they all still use the extended connecting rod which retains the previous problems of imparting side wall stress to the cylinder walls and flexation during moments of severe engine stress as aforesaid.
This invention is a novel development in the design of reciprocating, multi-cylinder internal combustion engines that solves all of the aforesaid problems. In this invention, the connecting rod is replaced by a combination of elements that provide for a sliding action in a plane lying normal to the axis of rotation of the crankshaft to convert the rectilinear motion of the reciprocating pistons into rotary motion of the crankshaft. In this invention, a plurality, and preferably two, adjacent pistons in separate cylinders are joined together by a carrier member at the open ends of the cylinders and slidably attached to a guide member that is pivotally connected to the offset throw of the output crankshaft. The carrier member and the guide member interact in sliding relationship during reciprocating motion of the pistons in a plane normal or perpendicular to the axis of the output crankshaft.
A number of benefits are derived from this new mechanical interconnection. In the first place, the reactive side thrust against the cylinders from the whipping action of the connecting rod is totally eliminated; all connection to the pistons remains axial throughout piston movement. The side-to-side sliding motion of the members has no significant lateral component against the cylinder walls. In addition, the initial power impulse from the traveling piston acts on an increasing torque arm for a full 90.degree. of crankshaft rotation ATDC to provide a longer and smoother power stroke on the crankshaft rather than in the power stroke previously described with respect to the standard connecting rod. Further, because there is no longer the need for the elongated connecting rod, engines may be made more compact, of lighter materials and the pistons and cylinders spaced closer to the crank shaft to make a more compact design and provide for better engine balance and smoothness of operation. Still further, engine balance and smoothness of operation are enhanced since the vertical motion of the piston pairs in their bores is simple harmonic in nature thus precluding net secondary forces that develop with connecting rods; elimination of these secondary forces as well as the reactive side thrust of the connecting rods permits the engine block and internal components to be made lighter weight than previously thought possible.